Conventionally, a tire forming apparatus employed in a single stage forming uses a single forming apparatus comprising a pair of right and left shoulder former sections and a central former section. Each of the shoulder former actions has a bead lock mechanism, and supports a shrunk ply turn-up bladder from inside by a cylindrical member to form a firm surface. The shoulder former sections are movable toward or away from to each other, namely, movable simultaneously in reverse directions along one axis. A tire component, such as ply, is wound around the outer circumference of the former sections to form a green carcass and a pair of right and left beads which are locked by bead lock mechanisms. Then, air is fed into the green carcass with the shoulder former sections being moved in toward each other in synchronization, to shape the green carcass toroidally and integrate it with a tread--belt assembly. Thereafter, both sides of the green carcass and side walls are wound up around the beads, whereby the green tire forming is accomplished. Such a tire forming apparatus is a so-called rubber former in which a flexible and expansible bladder is employed as the central, former section. So, there is a problem that an open joint is generated because when a tire component such as a ply is wound around the outer circumference of the former, jointing work is difficult to carry out. Accordingly, instead of the rubber former, a two-stage-overlapping-type forming apparatus was developed. In the apparatus, as shown in FIG. 7, each end of a pair of, right and left, cylindrical members 22A, 22B having hard surface which overlap over a full width with each other are fixed, concentrically with the sections 21A, 21B, to inner side surface of each shoulder former sections 21A, 21B to construct the center former section 23. When both former sections 21A, 21B are moved to remotest positions, both (right and left) cylindrical members 22A, 22B provide a predetermined necessary former width FW for forming a green carass. When both former sections 21A, 21B are moved toward one another for toroidally shaping the green carcass, both cylindrical members 22A, 22B overlap over a full width with each other. Namely, the members 22A, 22B are superimposed into a two layer unit (as shown in FIG. 7 by dotted lines) to shorten the former width FW into about a half width.
However, when a tire is formed with the two-stage-overlapping-type apparatus, the minimum distance at shaping between both shoulder former sections 21A, 21B, in other words, the distance BW.sub.1 between the beads in the completed green tire after shaping is, as shown in FIG. 8, inevitably limited to a half width of hard cylindrical elements 22A, 22B which regulate the former width FW (in FIG. 7). On the other hand, since the distance between the beads BW.sub.2 of a tire cured by a curing metal mold is much shorter than the distance BW.sub.1 between the beads of the green tire, the beads 25A, 25B are forcibly much moved inwardly toward each other during cure. As a result, undesirable wrinkles are generated on bead chafers and side walls, so that defective tires are produced. The object of the present invention is to solve such problem.
In FIG. 8, the solid line shows a carcass profile of a green tire made by the two-stage-overlapping-type forming apparatus, the one-dot chain line shows a carcass profile of a tire cured by a metal mold, and the dashed line shows a carcass profile of a green tire made by an apparatus of the present invention disclosed below. Numeral 29 represents a tread.